The polyphenylene ether resins are well known in the art as a class of thermoplastics which possess a number of outstanding physical properties. They can be prepared, in general, by oxidative and non-oxidative methods, such as are disclosed, for example, in Hay, U.S. Pat. Nos. 3,306,874 and 3,306,875 and Stamatoff, U.S. Pat. Nos. 3,257,357 and 3,257,358, which are incorporated herein by reference.
It is known that the polyphenylene ether resins can be combined with impact modifiers to obtain improved impact resistance and other mechanical properties. Suitable impact modifiers for polyphenylene ether resins are disclosed in Cizek, U.S. Pat. No. 3,383,435, incorporated herein by reference, and elsewhere.
As employed herein the term "plasticized" is used to describe compositions having a sufficient amount of plasticizer to reduce the temperature of optimum extrusion by at least about 25.degree. F., and normally from about 25.degree. to about 100.degree. F.
It has now been surprisingly discovered that plasticized polyphenylene ether compositions comprising a mineral reinforcing agent, possess enhanced stiffness, as measured by flexural modulus and flexural strength, in comparison with corresponding compositions without said agent. Moreover, it is unexpected that the improvements in stiffness properties are obtained along with a significant retention of ductility, as measured by tensile elongation and impact resistance.